Donor polymorphism of tumor necrosis factor gene: relationship with variable severity of hepatitis C recurrence after liver transplantation

Cytokine (IL-10, IL-6, TNF-α and TGF-β1) Gene Polymorphisms in Chronic Hepatitis C Virus Infection among Malay Male Drug Abusers

Cytokines play an important role in modulating inflammation during viral infection, including hepatitis C virus (HCV) infection. Genetic polymorphisms of cytokines can alter the immune response against this infection. The objective of this study was to investigate the possible association between chronic hepatitis C virus infection susceptibility and cytokine gene polymorphism for interleukin-10 (IL-10) rs1800896 and rs1800871, interleukin 6 (IL-6) rs1800795, TNF-α rs1800629, and TGF-β1 rs1800471 in Malay male drug abusers. The study was conducted on 76 HCV-positive (HP) male drug abusers and 40 controls (HCV-negative male drug abusers). We found that there were significant differences in the frequencies of genotype for IL-10 rs1800871 (p = 0.0386) and at the allelic level for IL-10 rs1800896 A versus G allele (p = 0.0142) between the HP group and the control group. However, there were no significant differences in gene polymorphism in interleukin 6 rs1800795, TNF-α rs1800629 and TGF-β1 rs1800471. These findings suggest significant associations between gene polymorphism for IL-10 rs1800871, IL-10 rs1800896 (at the allelic level) and susceptibility to HCV infection among Malay male drug abusers.

Recipient interleukin 6 gene polymorphism and expression predict HCV recurrence post liver transplantation

BACKGROUND

Liver transplantation (LTX)is a lifesaving- effective protocol for patients suffering end stage liver disease (ESLD) and its complications post HCV infection. Recurrence of disease is a frequent clinical complication that is observed in patients undergoing LTX. Cytokines play a central role in the immunological events occurring after the surgery.

METHODS

Using Allelic Discrimination PCR, the allelic variation G174C of IL-6 gene was investigated. The abundance of IL6- mRNA and plasma IL6 cytokine levels were evaluated by using qRT-PCR in peripheral blood mononuclear cells (PBMCs) and enzyme-linked immunosorbent assay (ELISA) respectively in 76 liver transplant recipients recruited from Al Sahel teaching hospital, Ministry of Health and Population Cairo Egypt within the period between June 2015 and October 2017.

RESULTS

The frequencies of IL-6 GG genotype and the G allele were significantly detected more in LTX recipients who experienced HCV recurrence versus those who did not suffer recurrence when compared to healthy controls (P = 0.001) and (P = 0.006), respectively. On the contrary, levels of IL-6 related transcripts in PBMC's of recurrent patients were indifferent from non-recurrent patients and healthy controls (P ≥ 0.124). Interestingly, the circulating IL-6 protein in plasma was significantly elevated in recurrent as compared to the non-recurrent recipients (P = 0.002).

CONCLUSION

HCV recurrence post liver transplantation occur more frequently in patients with -174 G/G IL-6 genotype and elevated plasma IL-6 levels.

Host nucleotide polymorphism in hepatitis B virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is etiologically linked with hepatitis B virus (HBV) and is the leading cause of death amongst 80% of HBV patients. Among HBV affected patients, genetic factors are also involved in modifying the risk factors of HCC. However, the genetic factors that regulate progression to HCC still remain to be determined. In this review, we discuss several single nucleotide polymorphisms (SNPs) which were reportedly associated with increased or reduced risk of HCC occurrence in patients with chronic HBV infection such as cyclooxygenase (COX)-2 expression specifically at COX-2 -1195G/A in Chinese, Turkish and Egyptian populations, tumor necrosis factor α and the three most commonly studied SNPs: PAT-/+, Lys939Gln (A33512C, rs2228001) and Ala499Val (C21151T, rs2228000). In genome-wide association studies, strong associations have also been found at loci 1p36.22, 11q22.3, 6p21 (rs1419881, rs3997872, rs7453920 and rs7768538), 8p12 (rs2275959 and rs37821974) and 22q11.21. The genes implicated in these studies include HLA-DQB2, HLA-DQA1, TCF19, HLA-C, UBE2L3, LTL, FDX1, MICA, UBE4B and PG. The SNPs found to be associated with the above-mentioned genes still require validation in association studies in order to be considered good prognostic candidates for HCC. Screening of these polymorphisms is very beneficial in clinical experiments to stratify the higher or lower risk for HCC and may help in designing effective and efficient HCC surveillance programs for chronic HBV-infected patients if further genetic vulnerabilities are detected.

Differential effects of donor and recipient IL28B and DDX58 SNPs on severity of HCV after liver transplantation

BACKGROUND & AIMS

IL28B single nucleotide polymorphisms are strongly associated with spontaneous HCV clearance and treatment response in non-transplant populations. A DDX58 single nucleotide polymorphism is associated with the antiviral response of innate lymphocytes. We aimed at evaluating the associations of donor and recipient IL28B (rs12979860 and rs8099917) and DDX58 (rs10813831) genotypes with severity of HCV recurrence after liver transplantation.

METHODS

In a case-control study of 523 liver transplantation recipients with HCV, we matched severe with mild recurrent HCV based on 2-year clinical and histologic follow-up. A total of 440 liver transplantation recipients (severe, n=235; mild, n=205) with recipient DNA and 225 (severe, n=123; mild, n=102) with both recipient and donor DNA were analyzed.

RESULTS

IL28B [rs12979860, non-CC (vs. CC) and rs8099917, non-TT (vs. TT)] in the recipient-only analysis had higher risk of severe recurrent HCV [OR 1.57 and 1.58, p<0.05]. However, for the 225 with donor and recipient DNA, IL28B rs12979860 CC (vs. non-CC) and rs8099917 TT (vs. non-TT) and DDX58 rs10813831 non-GG (vs. GG) were associated with more (not less) severe recurrent HCV. The greatest risk of severe recurrent HCV was for rs12979860 CC donors in non-CC recipients (OR 7.02, p <0.001, vs. non-CC donor/recipient) and for rs8099917 TT donors in non-TT recipients (OR 5.78, p=0.001, vs. non-TT donor/recipient). These associations persisted after controlling for donor age, donor race, and donor risk index.

CONCLUSIONS

IL28B and DDX58 single nucleotide polymorphisms that are favorable when present in the non-transplant setting or in the recipient are unfavorable when present in a donor liver graft.

Human liver transplantation as a model to study hepatitis C virus pathogenesis

Hepatitis C is a leading etiology of liver cancer and a leading reason for liver transplantation. Although new therapies have improved the rates of sustained response, a large proportion of patients (approximately 50%) fail to respond to antiviral treatment, thus remaining at risk for disease progression. Although chimpanzees have been used to study hepatitis C virus biology and treatments, their cost is quite high, and their use is strictly regulated; indeed, the National Institutes of Health no longer supports the breeding of chimpanzees for study. The development of hepatitis C virus therapies has been hindered by the relative paucity of small animal models for studying hepatitis C virus pathogenesis. This review presents the strengths of human liver transplantation and highlights the advances derived from this model, including insights into viral kinetics and quasispecies, viral receptor binding and entry, and innate and adaptive immunity. Moreover, consideration is given to current and emerging antiviral therapeutic approaches based on translational research results.

Trends in post-liver transplant survival in patients with hepatitis C between 1991 and 2001 in the United States

It has been suggested that the post-liver transplantation (LT) survival rate of patients with hepatitis C virus infection (HCV) has declined in recent years. To compare the outcome of LT in patients with HCV at various time intervals between 1991 and 2001, we used United Network for Organ Sharing data to compare the post-LT survival of adult patients (age >18 years) with HCV with those without HCV. Of the 37,101 patients who underwent LT during the study period, 28,193 patients (HCV 7,459 and 20,734 non-HCV) were eligible for the study. On the basis of the time of transplantation, patients were divided into 3 groups: 1991-1993 (period 1), 1994-1997 (period 2), and 1998-2001 (period 3). The patient and graft survival rates were adjusted for other known confounding variables that influenced outcomes. The 3-year patient survival rate was lower in HCV patients compared with non-HCV recipients (78.5% vs. 81.4%, hazard ratio 1.14, 95% confidence interval 1.05-1.23, P = 0.001). The graft (72.8%, 71.0%, and 69.8%) and patient (77.4%, 79.6%, and 78.5%) survival of HCV patients remained unchanged during study periods 1-3, respectively. However, the graft and patient survival rates of non-HCV recipients improved markedly during study periods 2 and 3 compared with period 1. The graft and patient survival has remained unchanged between 1991 and 2001 in HCV recipients, but during the same period, there was a great improvement in survival among non-HCV recipients.

Associations of tumour necrosis factor alpha promoter polymorphisms at position -308 and -238 with clinical characteristics of chronic hepatitis C

The aim of this study was to investigate the association between G vs A transitions in the promoter region of the tumour necrosis factor (TNF) alpha at positions -308 (TNF308.2) and -238 (TNF238.2) and clinical features of chronic hepatitis C (CHC). These two promoter TNF-alpha variants were determined in 250 biopsy-proven CHC patients by polymerase chain reaction amplification, followed by the Restriction Fragment Length Polymorphism (RFLP) method. The distribution of -308 and -238 TNF-alpha promoter genotypes were TNF308.1/TNF308.1: 187 (74.8%), TNF308.1/TNF308.2: 57 (22.8%) and TNF308.2/TNF308.2: 6 (2.4%), respectively, and TNF238.1/TNF238.1: 247 (98.8%) and TNF238.1/TNF238.2: 3 (1.2%). The frequencies of the TNF308.2 and TNF238.2 promoter alleles were 13.8% and 0.6%. Increased TNF308.2 allele copy numbers were significantly associated with increased frequency of lower pretreatment hepatitis C virus (HCV) RNA levels (<800 000 IU/mL; P = 0.031) and severe fibrosis stage (F3-F4; P = 0.006) and higher mean fibrosis score (P = 0.007). The higher cytokine production (with one or two TNF308.2 alleles) was correlated significantly with lower pretreatment HCV RNA levels with a lower mean HCV RNA level (P = 0.024) and increased frequency of lower pretreatment HCV RNA levels (<800 000 IU/mL; P = 0.017). Stepwise logistic regression showed that higher fibrosis score and low HCV RNA levels were independently related to the TNF308.2 allele [odds ratio (95% CI): 1.385 (1.127-1.702) and 0.698 (0.488-0.990)]. We conclude that inheritance of the TNF-alpha promoter genotype at the position -308 appears to be associated with variability in severity of fibrosis and viral load in chronic HCV infection.

Allograft TNFbeta and IL16 polymorphisms influence HCV recurrence and severity after liver transplantation

Hepatitis C (HCV) recurrence after liver transplantation is universal although severity varies. We explored whether certain donor cytokine gene polymorphisms may be useful markers of susceptibility to severe recurrence. Allograft tumor necrosis factor (TNF) beta and interleukin (IL) 16 gene polymorphisms were correlated with l-yr clinical outcome among HCV+ recipients. Recipients of donor TNFbeta(2,2) (n = 8) experienced less recurrence (50% vs. 71%, P < 0.05), less fibrosis (25% vs. 76%, P < 0.01), and less rejection (25% vs. 71%, P < 0.01) than donor TNFbeta(1,1) (n = 19). Recipients of donor TNFbeta(1,2) (n = 27) demonstrated an intermediate picture with less fibrosis (56%, P < 0.01) and less rejection (37%, P < 0.01) than TNFbeta(1,1). Recipients with donor IL16(TC) (n = 22) showed less recurrence (65% vs. 78%, P = 0.05), less fibrosis (53% vs. 67%, P = 0.06), and less rejection (41% vs. 55%, P = 0.06) than IL16(TT) (n = 32) genotype. Recipients of the combination TNFbeta(2,2)/IL16(TC) donor genotype had the most benign clinical outcome with less recurrence (33% vs. 75%, P < 0.01), no fibrosis (0% vs. 50%, P < 0.001), and fewer rejections (33% vs. 75%, P < 0.01) than donor TNFbeta(1,1)/IL16(TT) genotype. In vitro production of cytokines correlated with genotype. Release of soluble TNFbeta for TNFbeta(1,1) vs. TNFbeta(1,2) and TNFbeta(2,2) was 4803 +/- 2142 pg/mL vs. 5629 +/- 3106 (P = not significant [ns]) and 7180 +/- 3005 (P = ns). Release of soluble IL16 for IL16(TT) vs. IL16(TC) was 437 +/- 86 pg/mL vs. 554 +/- 39 (P = 0.06). In conclusion, allograft TNFbeta and IL16 gene polymorphisms may be useful markers to predict the severity of disease recurrence among HCV+ patients after liver transplantation.

TNFalpha genotype affects TNFalpha release, insulin sensitivity and the severity of liver disease in HCV chronic hepatitis

BACKGROUND/AIMS

TNFalpha induces insulin resistance and promoter polymorphisms of TNFalpha gene affect the release of this cytokine, implicated in the pathogenesis of HCV-related diabetes and fatty liver. The aim was to define whether in patients with HCV chronic hepatitis TNFalpha genotype influences TNFalpha activity, insulin resistance, and the severity of the disease.

METHODS

186 patients, 65% with steatosis, 17% with diabetes. TNFalpha and sTNFR2 were determined by ELISA, insulin resistance by HOMA-R index and TNFalpha -238, -308, and -863 polymorphisms by restriction analysis.

RESULTS

TNFalpha, sTNFR2, and insulin resistance were higher in patients than in 89 controls. TNFalpha pathway activity was correlated with LDL cholesterol, steatosis, and insulin resistance, which, in turn, was correlated with the severity of liver damage. Patients subdivided according to TNFalpha genotype significantly differed for TNFalpha release, insulin sensitivity and the prevalence of cirrhosis. The -308 and -238 TNFalpha polymorphisms, characterized by increased promoter activity, were associated with higher TNFalpha activity, insulin resistance and severity of the disease, whereas the -863 polymorphism, characterized by reduced promoter activity, with lower TNFalpha activity, and higher insulin sensitivity.

CONCLUSIONS

TNFalpha genotype modulates the activity of the TNFalpha pathway, influences insulin sensitivity and the severity of HCV chronic hepatitis.

Cytokine gene polymorphisms and the susceptibility to liver cirrhosis in patients with chronic hepatitis C

BACKGROUND

The speed of fibrosis progression varies considerably between patients with chronic hepatitis C. This study analyzed whether cytokine gene polymorphisms are associated with a progressive course of the disease.

METHODS

Leukocyte DNA from 101 patients with chronic hepatitis C, 52 patients with hepatitis C virus (HCV)-induced cirrhosis and 200 Caucasian blood donors was prepared. Using PCR, RFLP and PAGE, gene polymorphism analysis of the interleukin (IL)1alpha( - 889), IL1beta( - 511 and +3954), IL1 receptor agonist (RA)(intron2 VNTR), IL4(intron3 VNTR) and TNFalpha( - 308) loci was performed.

RESULTS

Of the polymorphisms analyzed, IL1beta( - 511) and IL1RA(intron2 VNTR) were unevenly distributed between the study groups. The IL1 (- 511)*A2A2 genotype occurred significantly more often in chronic hepatitis C and HCV-induced liver cirrhosis than in the controls (P < 0.01, P < 0.05, respectively). Patients with HCV-induced cirrhosis displayed a significantly higher frequency of the IL1RA(intron2 VNTR)*A2 polymorphism than patients with chronic hepatitis C and controls (P < 0.05).

CONCLUSIONS

Although the IL1beta( - 511)*A2A2 genotype may increase the susceptibility to acquire chronic hepatitis C and IL1RA(intron2 VNTR)*A2 polymorphism is associated with disease progression to cirrhosis, our results indicate that the analyzed cytokine gene polymorphisms have an overall low impact on the natural course of chronic hepatitis C infection.

Host and donor risk factors before and after liver transplantation that impact HCV recurrence

1. The natural history of hepatitis C after liver transplantation is variable. Several factors, including those related to the virus, the host, the environment and the donor, are probably implicated in the outcome. 2. The immune status per se likely represents the main significant variable in influencing disease severity in hepatitis C virus-infected patients. Findings that support this statement include the higher aggressivity of hepatitis C in immunocompromised liver transplant recipients as compared with that observed in immunocompetent patients, both before and after the development of compensated cirrhosis, and the significant association described between the degree of immunosuppression and disease severity. 3. Similar to that observed in the immunocompetent population, the age at the time of infection (age of the donor) strongly affects posttransplantation hepatitis C virus-related disease progression. 4. Hepatitis C-related disease progression is faster in patients who underwent transplantation in recent years as compared with those who underwent transplantation in earlier cohorts. The increasing age of the donor and the use of stronger immunosuppression may, in part, explain the worse outcomes seen in recent years. 5. Additional host-related variables predictive of outcome include the immunogenetic background, the timing of recurrence, and the early histologic findings.

Tumor necrosis factor alpha promoter polymorphisms at position -308 in Taiwanese chronic hepatitis C patients treated with interferon-alpha

A G-to-A polymorphic sequence at position -308 in the tumor necrosis factor alpha promoter (TNF308.2) might be associated with disease susceptibilities. To investigate the association between -308 TNF-alpha variants and pathogenesis of hepatitis C virus (HCV) infection and response to interferon-alpha (IFN-alpha) treatment for chronic hepatitis C (CHC), -308 TNF-alpha genotypes were determined in 100 unrelated Taiwanese CHC patients treated with IFN-alpha and in 100 unrelated healthy subjects. The distribution of -308 TNF-alpha genotypes did not differ between CHC patients and controls. Age, sex, HCV genotype, and the necroinflammatory activity of liver histopathology did not differ among CHC patients with different -308 TNF-alpha genotypes. Although pretreatment HCV RNA serum levels, aminotransferase and the rate of severe fibrosis decreased with the copy number of TNF308.2, the difference did not reach significance. We failed to demonstrate any association between -308 TNF-alpha promoter polymorphisms and response to IFN therapy, which was inversely correlated to liver cirrhosis, pretreatment serum HCV RNA levels and genotype 1b by using multivariate analysis. In conclusion, our findings suggest that -308 TNF-alpha promoter polymorphisms do not play a direct role in the susceptibility and pathogenesis of HCV infection, and in the response to interferon-alpha therapy for CHC.

Hepatitis C virus in the human liver transplantation model

Hepatitis C virus-related liver failure is the single leading indication for liver transplantation, and the study of HCV in the transplant setting has enhanced the understanding of the natural history of disease and putative mechanisms by which HCV causes liver injury. In a subset of patients, allograft cirrhosis develops within a few years after transplantation, and recent findings suggest these individuals are immunologically impaired compared with individuals with mild HCV recurrence at long-term follow-up. Fig. 9 shows a conceptual paradigm of mechanisms potentially involved in shaping HCV outcome after transplantation. It is possible that relative antiviral control by innate and adaptive immune responses (to maintain HCV replication below a certain threshold) prevents direct cytopathic injury and induction of oxidative stress and apoptosis of cells. Additional phenomena that may contribute to induction of apoptosis (eg, genetic polymorphisms within the donor organ. CMV coinfection, and ischemic-preservation injury) may augment the initial cascade of liver injury. Recruitment to the allograft of nonspecific cells may decrease viral replication by way of noncytolytic mechanisms or augment viral replication (eg, Th2 phenotype) and direct cytopathic injury. The immune response is likely insufficiently vigorous to keep viral replication under control, but may maintain chronic liver injury. The liver transplant model is unique in that distinct phenotypic outcomes can be observed over a short period of time. A consideration of the temporal evolution of different mechanisms is also important, because mechanisms that initially predominate may become less important over time, and conversely, as suggested with the inverse correlation between viral load at 5 years and allograft fibrosis, new immune responses may emerge that modify the host-virus interaction. Prospective characterization of the immunoregulatory and virologic mechanisms involved in the liver transplantation model hopefully will help unravel the causal basis of reported associations, lead to the development of highly specific therapeutic strategies, and ultimately diminish the rate of graft loss from recurrent disease.

Interleukin-1beta gene polymorphisms associated with hepatocellular carcinoma in hepatitis C virus infection

Hepatitis C virus (HCV) infection is a major risk factor for developing hepatocellular carcinoma (HCC), a life-threatening sequel. However, the factors that affect disease progression to HCC have not been thoroughly elucidated. Genetic polymorphisms in proinflammatory cytokines, the interleukin 1 (IL-1) family (IL-1beta and IL-1ra) and tumor necrosis factor-alpha (TNF-alpha), were studied in 274 Japanese patients with chronic HCV infection and 55 healthy individuals using standard polymerase chain reaction-based genotyping techniques. The association between these polymorphisms and disease status was evaluated while controlling for confounding clinical variables. The proportion of patients with HCC in the IL-1beta-31 T/T (55%, odds ratio to C/C was 2.63, P =.009) genotype was higher than in the T/C (44%, odds ratio to C/C was 1.64, P =.149) and C/C genotypes (35%). The IL-1beta-31 and -511 loci were in near complete linkage disequilibrium, and the IL-1beta-511/-31 haplotype C-T was significantly associated with the presence of HCC (odds ratio of 1.51, P =.02). Polymorphisms in the TNF-alpha gene were not associated with disease. A multivariate analysis revealed that the IL-1beta-31 T/T genotype, alpha-fetoprotein >20 microg/L, presence of cirrhosis, male sex, and age >60 years were associated with the presence of HCC at odds ratios of 3.73 (T/T vs. C/C), 4.12, 4.03, 3.89, and 3.27, respectively. In conclusion, the IL-1beta-31 genotype T/T or the IL-1beta-511/-31 haplotype C-T is associated with the presence of HCC in Japanese patients with chronic HCV infection.

Impact of human herpesvirus-6 on the frequency and severity of recurrent hepatitis C virus hepatitis in liver transplant recipients

A role of tumor necrosis factor-alpha (TNF-alpha) In the immunopathogenesis of hepatitis C virus (HCV) infection has been proposed. The novel herpes virus, human herpes virus-6 (HHV-6), is amongst the most potent inducers of cytokines, including TNF-alpha. The impact of HHV-6 viremia on the progression of recurrent HCV hepatitis was assessed in 51 HCV-positive liver transplant recipients. The frequency of recurrent HCV hepatitis did not differ between patients with HCV viremia (47.6%, 10/21) as compared with those without HCV viremia (46.7%, 14/30, p = 0.9). However, the patients with HHV-6 viremia had a significantly higher fibrosis score upon HCV recurrence than those without HHV-6 viremia (mean 1.5 vs. 0.3, p = 0.01). An association between cytomegalovirus (CMV) viremia and HCV recurrence was not documented; 50% (15/30) of the patients with CMV viremia and 42.8% (9/21) of those without CMV viremia had recurrent HCV hepatitis (p > 0.5). Receipt of ganciclovir (administered upon the detection of CMV viremia) was associated with lower total Knodell score (mean 5.2 vs. 6.9, p = 0.05) and a trend towards lower fibrosis score (mean 0.44 vs. 1.00, p = 0.12) in patients with recurrent HCV hepatitis. Thus, HHV-6 viremia in HCV-positive liver transplant recipients identified a subgroup of patients at increased risk for early fibrosis upon HCV recurrence.

Tumor necrosis factor alpha promoter polymorphisms influence the phenotypic expression of hereditary hemochromatosis

Severe iron overload usually develops in patients with hereditary hemochromatosis (HHC), but variability in the phenotypic expression of the disease has been reported. This study assessed whether tumor necrosis factor alpha (TNF-alpha) plays a role in phenotypic expression of HHC. Sixty-four patients with HHC and 172 healthy volunteers (controls) were studied. Release of TNF-alpha from stimulated peripheral blood monocytes was measured by enzyme-linked immunosorbent assay, and 308 and 238 TNF-alpha polymorphisms were detected with polymerase chain reaction and restriction fragment-length polymorphism analysis. The relation between TNF-alpha polymorphisms and clinical expression of HHC was evaluated. Patients with HHC released less TNF-alpha than controls, but the difference was significant only in homozygotes for the C282Y mutation. The prevalence of the 308 TNF-alpha polymorphism was similar in patients and controls, whereas the prevalence of the 238 polymorphic allele was significantly lower in patients (3% versus 16%; P =.002). A lower prevalence of cirrhosis was observed in patients with TNF-alpha polymorphism than in those without it (4 of 15 [27%] versus 28 of 49 [57%]), but the difference was not significant (P =.07). In nonhomozygotes for the C282Y mutation, severe liver siderosis was less prevalent in patients with the 308 polymorphism than in those without it (P =.05). Alanine aminotransferase (ALT) values were significantly lower in patients with TNF-alpha polymorphism (P =.006), even when patients with other hepatotoxic factors were excluded. Multivariate analysis showed that TNF-alpha polymorphism was independently associated with ALT values (P =.0008 and P =.045, respectively, in homozygotes and nonhomozygotes for the C282Y mutation) and siderosis in nonhomozygotes (P =.047). Thus, TNF-alpha appears to play a role in HHC by modulating the severity of liver damage. (Blood. 2001;97:3707-3712)

Role of cytokine gene polymorphism in hepatitis C recurrence and allograft rejection among liver transplant recipients

BACKGROUND

Cytokines play a key role in the regulation of immune responses. The maximal capacity of cytokine production varies between individuals and was shown to correlate with polymorphism in cytokine gene promoters. The objective of this study was to analyze the role of cytokine allelic variations in susceptibility to early graft rejection episodes and recurrence of hepatitis C infection in liver transplant (LTx) recipients.

METHODS

The genetic profile of five cytokines was studied in 68 LTx recipients and 49 controls using polymerase chain reaction sequence specific primers. All individuals were genotyped as high or low producers of TNF-alpha and IL-6 and high, intermediate, or low producers of transforming growth factor beta (TGF-beta), interferon gamma (IFN-gamma), and interleukin 10 (IL-10) based on single nucleotide substitutions.

RESULTS

No statistically significant differences were observed between patients with or without early rejection episodes. A significant proportion of patients more prone to rejection were genotyped as having a low production profile of IL-10 compared with the control population (P=0.04). These data are in accordance with reports regarding other solid-organ transplant recipients. Patients with no recurrence of hepatitis C had the inherent ability to produce higher TGF-beta levels than did patients with recurrent disease (P=0.042). Among nonrecurrent patients, the percentage of genetically low IL-10 producers was higher than among recurrent patients (P=0.07). Furthermore, a genetic tendency to produce higher levels of IFN-gamma was noted among LTx recipients with nonrecurrent hepatitis C than among those with recurrent hepatitis C.

CONCLUSIONS

While no significant correlation was detected between particular cytokine profile and early rejection episodes, our data strongly suggest an association between cytokine gene polymorphism of TGF-beta, IL-10, and INF-gamma and recurrence of hepatitis C in LTx recipients.

Role of cytokine gene polymorphisms in acute rejection and renal impairment after liver transplantation

Although immunosuppressive regimens are effective, rejection occurs in up to 50% of patients after orthotopic liver transplantation (OLT), and there is concern about side effects from long-term therapy. Knowledge of clinical and immunogenetic variables may allow tailoring of immunosuppressive therapy to patients according to their potential risks. We studied the association between transforming growth factor-beta, interleukin-10, and tumor necrosis factor alpha (TNF-alpha) gene polymorphisms and graft rejection and renal impairment in 121 white liver transplant recipients. Clinical variables were collected retrospectively, and creatinine clearance was estimated using the formula of Cockcroft and Gault. Biallelic polymorphisms were detected using polymerase chain reaction-based methods. Thirty-seven of 121 patients (30.6%) developed at least 1 episode of rejection. Multivariate analysis showed that Child-Pugh score (P =.001), immune-mediated liver disease (P =.018), normal pre-OLT creatinine clearance (P =.037), and fewer HLA class 1 mismatches (P =.038) were independently associated with rejection. Renal impairment occurred in 80% of patients and was moderate or severe in 39%. Clinical variables independently associated with renal impairment were female sex (P =.001), pre-OLT renal dysfunction (P =.0001), and a diagnosis of viral hepatitis (P =.0008). There was a significant difference in the frequency of TNF-alpha-308 alleles among the primary liver diseases. After adjustment for potential confounders and a Bonferroni correction, the association between the TNF-alpha-308 polymorphism and graft rejection approached significance (P =.06). Recipient cytokine genotypes do not have a major independent role in graft rejection or renal impairment after OLT. Additional studies of immunogenetic factors require analysis of large numbers of patients with appropriate phenotypic information to avoid population stratification, which may lead to inappropriate conclusions.

Viral hepatitis in the liver transplant recipient

Understanding and management of HBV and HCV infection in the OLT recipient has evolved rapidly in the last decade. The spontaneous risk for viral recurrence after transplantation is high, but has been decreased effectively in hepatitis B-positive recipients with the use of HBIG and lamivudine. HCV recurrence as defined by histologic injury is almost universal, although graft or patient outcomes for the first 8 years after OLT do not appear to be limited by HCV serostatus. However, effective prophylactic regimens that alter the natural history of HCV reinfection do not currently exist, and with longer follow-up into the second decade, the prevalence of HCV-related graft failure is likely to increase.

Disease recurrence following liver transplantation

Virtually all liver diseases that necessitate orthotopic liver transplantation (OLT) can recur, and recurrent disease has the potential to become the most serious problem facing transplantation in the future. In addition, recurrence following transplantation provides a model to study pathogenic mechanisms of these diseases. While some interventions (e.g., HBIG) have been shown to alter the natural history of recurrent disease, most of these disease processes are not modified by our currently available therapies. In addition, the role of different immunosuppressive protocols on disease recurrence requires further definition. As a varying proportion of the first generation of liver transplant patients develop severe recurrence and graft failure, policies of organ allocation for retransplantation will be challenged.